Today’s ACT science question of the day is a data interpretation question. (Basically, we have to read a data table.)
We are given a table of sediment concentrations at various depths that’s something like this:
| Depth (cm) |
Temperature (oC) |
pH | Concentration in sediment (ppm) | |||||
| SO42– | S2– | CO2 | Fe3+ | Fe2+ | O2 | |||
| 0 | 4 | 7.0 | 7.0 | 0.0 | 1.0 | 4.0 | 0.5 | 2.0 |
| 5 | 5 | 6.5 | 5.0 | 2.0 | 1.5 | 3.0 | 1.5 | 1.0 |
| 10 | 7 | 6.0 | 3.5 | 3.5 | 2.0 | 2.0 | 2.0 | 0.0 |
| 15 | 9 | 5.5 | 3.3 | 3.8 | 3.0 | 0.8 | 3.8 | 0.0 |
| 20 | 10 | 5.0 | 3.0 | 4.0 | 1.0 | 0.5 | 4.0 | 0.0 |
The test maker would like us to tell them which ion and dissolved gas has a constant concentration at depths of 10 cm or more.
First step: find the depth information (left column). We need to look at the last three depths: 10cm, 15cm, and 20cm.Next step: ignore the temperature and pH columns since they don’t apply to our question.Final step: take a gander at the columns of concentration info for the various ions and dissolved gases. Which one is constant (the same) in the last three rows?Only O2 fits the bill. Even though its value is 0, it is 0 in all three rows; the other options all vary across the range of depths.If you focus on what the question is asking you to find, questions like this one are pretty simple! Don’t get caught up worrying about what the various symbols mean or looking at data points that aren’t relevant to the question…don’t worry, you’ll have more questions that will allow you to work with the other info!